Common signs that life is built to survive, from humans to bacteria

Column: Links between man and microbe, and how life can survive in unexpected places.

By
Robert C. Cowen, Columnists for The Christian Science Monitor /
April 16, 2009

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Bacteria in a Petri dish.

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Scientists studying the robustness of organic life have found some unexpected capabilities in nature. For one research team, it's the ability of former light-loving and oxygen "breathing" marine microbes to make do with only iron and sulfur when shut up in a nasty place. For another group, it's the realization that a common construction strategy underlies most, if not all, of Earth's plants and animals. This similarity could be an advantage in adapting to a wide variety of environments and changing circumstances.

"The big idea is that cells, tissues, and organisms hailing from all limbs of the tree of life respond to stimuli using basic biological 'modules,’ " says a recent announcement from the University of California at San Diego.

As UCSD bioengineer Adam Engler and colleagues explained in an overview report in Science, "module" means the way biological functions come together to allow individual living cells to form larger structures. This includes how structures such as weight-bearing bones are built in responses to external forces.

When Dr. Engler looks at these ways that cells stick together, he sees that they are fundamentally similar in humans and bacteria. According to the UCSD announcement, he thinks that this shows there is something inherent in nature.

That's thinking outside the traditional research boxes. It's insight that has come from such diverse experts as stem cell biologists, engineers, and mathematicians working together. Engler says that "we have arrived at an interesting way to describe known biological processes and bring concepts together that are traditionally not considered."

Speaking of thinking outside of the box, biologists didn't expect to find microbes under the Taylor Glacier outlet of the East Antarctic Ice Sheet. It's a lousy place to live – cold, dark, no oxygen. Yet Jill Mikucki at Dartmouth College and colleagues now have unequivocal evidence that some microbes find it a happy home. These are not so-called extrophiles, such as those that have evolved to live under harsh conditions. They appear to be the descendants of photosynthetic marine organisms that "breathed" oxygen. They now have adapted by replacing a metabolism using oxygen with one using iron and sulfur.

As Dr. Mikucki and colleagues explain in a paper in Science, they are studying the microbes' metabolism where they emerge from the end of the glacier as an iron-rich red stain. It appears that an ancient inlet was trapped on land when sea level fell. Then the briny pond was capped by glacial ice. Co-author and Harvard professor Ann Pearson says, "It's a bit like finding a forest that nobody has seen in 1.5 million years." Further study of this unusual life may give clues to how life might have evolved on Mars or survived the "Snowball" Earth period when our planet was totally ice covered.

Whether you look at Engler's big idea or focus on Taylor Glacier microbes, Earthly life seems built to survive. No guarantees, however, for what form that life may take.